Fiber forming solutions



Patented Oct. 7, 1952 assignment to The Cheinstrand-Corporatitin',

a corporation of Delaware No Drawing. Application'sept'einber 26, 1950, Serial No. 186,999

or more acrylonitrile and up to 20*perc"e'xit"dfo"ther monomers, such as vinyl acetate, met'hyl'methacrylate, methyl acrylate, styrene, vinylide'rie chloride, and methacrylonitr ile are capable of production into fibers with superior physicalproperties. Althoughfibe'rs so prepared-have superior tensile properties; desirable elongation; and excellentstability over a wide range of-physical and chemical conditions, they are subject to certain inherent disabilities" which greatly r'estrict their utility as general purpose fibers. For example, these compositions and the fibers-prepared therefrom do not-have suflicient dye ,affinity to enable the development of satisfactory colored fibers. Furthermore many ofthe com?- positions are diflicult toprepare insuitable-solu tions, due to viscosity increases, gellation and the development of cloudy solutions when con ventional fiber spinning-procedures ane-practiced;

In copending applicatiomBer-ial No. 158332} filed April 26, 1950, by David: W. Chaney and" Howard M. Hoxie, there are. described and claimed new fiber spinning compositions, which have the desirable fiberproper-tie'so'f theprior art acrylonit'rile polymers, but'whichliaveimus ual receptivity for dyestuffs." lnacccrdfancwith this procedure the undyeable acry'oni-ti il= poly-' mers are blended-with polymerswhich' are in herently better dye acceptors; 'Ihejblendewpoly: mer not only acquires satisfactory-fdye-receptivity' but is also found to havejan unusually superior thermostability. In the spinning-of thebls'nded polymers it has beenfound'that heterogeneous cloudy solutions, partial gellatiori", ncreasesin' viscosity and otherirregularitiesfare frequently encountered. v A I The fundamental purposeof this invent on is? to provide means of the improved .spiniiiii'g'oi the blended polymers; A rurtnerpurooseortne' invention is'to'provide a nie'aiisof rejdi'icingl tlie viscosity and increasingthe spinnabilitylof the solution Without'lower'ing the solidcont'ent; and

conversely, increasing thesolidcontent of a. spinning solution without increasing. the viscosity. A stillfurther purposeis tceliminate the-cloudiness and other heterogeneous irregularitiesiri mer may be'dissolved in conyentional solventsfor' fiber forming acrylonitrile polymers to producesolutions of unusual-quality with respect to homo,- geneity'and' spinnabi-lity if the solutions a re grade in thepresence of a;minor proportion of sulfuricacid; for exampleirom 0.01 to; 3.90 weight per cent based on the solution. Preferred practice ultilizes from-0.05 to"1.00-percent. Such' mixtureshave been foundtohave lower viscositiesand" complete'ireedom from turbidity as com pared to thesame-solutions: not containing the sulfuric acid.'- Although the' invention is particularly applicable to blended VinyIpy'ridine polymers'; wliere" heterogeneous properties are fre quent andthe minimization thereof a commonproblem, the inventioniiszalso usefulwith respect" to 'copolymers .of acrylonitrile" and vinylpyridiiie, particularly'the copolyme'r's'o'f 90 to 98 per cent acrylo'riitrile 'and from two to tenper cen'tof a vinylpyridiiie' or an ,alkyi substituted vinylpyri-" dine. 1

Theinverition isapplicable to both blends and copolymers which are comprised of from two to ten per cent of a vinylpyridiiie' or an" alkyl sub"- sftituted vinylpyri'dihe} said percentage lcieirie' based on th'e torn-mar ners o' hicli the' cofioly mer or blendof copdlyiners' are empnsea; The blends may have as the principal polymer from to 98' per c'entoi a c'opolym'er of or more" per cent acrylonitrile' and minor proportions of monomers"copolymerizable' therewith. The other" blend constltiientis a poyvinylpyridine'or aico' polymer-jot 3pm" more per cn'tof Tavinylpy'ridin'e' or alkyl substituted vinylpyr'idine" and 'up't'd'l'fl per cent of another ,copolyn erizable mono: er; The two components of the" blended copolyniei'sf are proportioned such .asto' provide the requir' quantity or I acrylonitrile and reactivevinylpyii dine.

rne' vinylpyridin'elinboth thec' poiyhiiiaiir blend copolymers may be anyyiliyl'py o'r' alkyl' s'ubstituted vinylpyridinel restrain '-2- viny1pyridine aturate-nin 'r-v i-yip id 119; aunts-endp int 1 a i sthynt. .5-v nr :me hr fid -z v li w l inez-v n r me hrl r d e -i y- FS- t ylpr dinel n a th r y' r in tamingalkylsubstituentswherein the all-zyl 'radical has up to fqur'carbonatbms.

leate, diethyl fumarate and other alkyl maleates and fumarates wherein the alkyl radical has up to four carbon atoms, styrene and other vinyl substituted aromatic hydrocarbons, vinylidene chloride and methacrylonitrile. These non-functional monomers may be present as a third monomer with acrylonitrile and a vinylpyridinein a terpolymeric system, or they may be used in the blended composition either as a comonomer with acrylonitrile in the principal polymer or as a comonomer with a vinylpyridine in the blending polymer. Y

The principal acylonitrile polymers and copolymers thereof may be prepared in any of the manners well-known to the art. Of particular utility are the emulsion or dispersion polymerizations which take place in a'n aqueous'medium in the presence of water-soluble peroxy compounds or other free radical type of catalysts and with a suitable dispersing agent. Such polymerizations may take place at elevated temperatures utilizing reflux conditions to eliminate the heat of polymerization or the reaction may be conducted by the Redox" methods in lower ternperatures. It is also conventional to use regulators, for example the various mercaptans, such as tert.'-dodecyl mercaptan, mercapto acetic acid, and the esters of mercapto acetic acid. The separation of the acrylonitrile polymers from the aqueous medium may be accomplished by filtration or decantation followed by drying in the manner well-known to the art. I

The vinylpyridine polymers .may'be bymass polymerization methods, solution polymerization methods, or aqueous emulsion procedures, the latter being the preferred manner of preparation. The preferred procedure involves the use of efficient emulsion stabilizing agents for the purpose of preventing a lomeration with the polymer particles. The details of polymerization procedure and separation of the polymer from the reaction medium may be practiced by anyof the numerous methods known to the art.

The fiber forming acrylonitrile polymer and vinylpyridine polymers are physically blendedby a wide variety of procedures. If desired the emulsions or dispersions of polymers in aqueous media, just as received from the polymerization reactors may. be blended. Physical mixtures of the separated solid polymers may also be'utilized. A preferred manner of preparing "the mixtures involves'the dispersion of the: polymers, or the emulsions thereof, in a solvent, with the distilla tion or evaporation of the water, if present in proportions large enough to interfere with the complete dissolution of the solid polymers. ,In the-preparation oi the blends in the presence of a conventional solvent, or preferably N,'N-dimethylacetamide, from which thefiber spinning will ultimately take place, frequently non-homogeneous, cloudy dispersions are obtained.

Other solvents which may be fused inthe practice of this invention are butyrolactone, N,N-dimethylformamide, ethylene carbonate, 'maleic' anhydride, N,N-dimethylmethoxyacetamide, succinic anhydride, and a-cyano'acetamide- In accordance with the practice of this inven tion minor proportions of sulfuric acid are added. It has been found that the addition of 0.01 per cent to five per cent by weight (based on the solvent) of sulfuric acid will eliminate the turbidity and produce clear, transparent, light-col ored polymer solutions; The treatment has also been found to cause a marked reduction in the viscosity, thereby enabling the spinning with 'higher solid content in the spinning solutions or spinning at low temperatures. Improvements in dye receptivity and dye fastness were noted. Further details of the invention are set forth with respect to the following specific examples:

Example 1 polymer of 97 per cent acrylonitrile and three per cent vinyl acetate with 16 per cent of a copolymer of 50 per cent vinyl pyridine and 50 per cent acrylonitrile in sufficient N,N-dimethylacetamide to yield an 18 per cent solids solution. The resulting solutions were found to be turbid and to have a viscosity of 117 poises at 50 C. Several samples of this spinning solution were treated with varying proportions of sulfuric acid. The following table demonstrates that improvements in viscosity and clarity of the solution are obtained by the addition of sulfuric acid to the spinning solution.

Y Viscosity gi gggf in Clarity of Solution 50035638 Turbid ll? Clear, light in color. 92

Cloudy 90 Example 2 The effect of sulfuric acid on spinning solutions of higher solids content was demonstrated by preparing a 24. 5 per cent solids content spinning solution of the copolymer blend described in the preceding example. The untreated solution was found to be cloudy and to have a viscosity of 371 poises .at 50 C. The addition of 0.2 cc. of sulfuric acid per 300 grams of solution clarified the solution. entirely and reduced the viscosity to 324 poises at 50 C.

-- Example 3 -A mixture of 622.5 parts by weight of N,N-dimethylacetamide, 112.2 parts of a copolymer of 97 per cent of acrylonitrile and three per cent vinyl acetate and 15.3 parts of a copolymer of 50 per cent of pyridine and 50 per cent acrylonitrile was prepared by stirring the mixture at C. for one hour. Sulfuric acid in the amount of 0.38 part by weight was added thereto, thereby forming a clear and homogeneous spinning solution. The solutionwas spun through a spinneret having 30 apertures each 0.005 inch in diameter into a mixture of 60 per cent N,N-di- 'methacetamide'and 40 per cent water. The fiber Example 4 Using the procedure described in Example 1, a copolymer of Q'Tpercent acrylonitrile and three ing; 0.19. percent of foundtober"edjiceii" Emmp e6-+ A series of blends f vvarious proportion copolymer-of 07 percent acrylonitrileandi three percent vinyl acetate, a "copolymer off50 percent vinylpyndine andj-50 percentfacrylonitrile were prepafedjdissolved in N ,N dimethyl'acetamide and treated with sulfuric acid in difierent proportions. The solutions soobtained were all spun into fibers which had excellent dye acceptance. The following table shows thevariation in proportions used and the cataract-the spinning solution l Wt. Percent V Sillfiir'ic 4 Acid Wt. Percent vinylpyridine Clearand homogeneous.

Do. Cloudy. Clear and homogeneous.

These experiments demonstrate that when more than one percent of sulfuric acid is used, cloudy solutions may be formed. This lack of clarity does not affect the spinnability of the solution. Improvements in lowered viscosity are found at all concentrations.

The invention is defined by the following claims.

What I claim is:

1. A fiber spinning solution comprising a solvent for fiber-forming acrylonitrile polymers, polymer of monomeric substances of which from two to ten percent of the total monomer is a vinylpyridine and at least 80 percent is acrylonitrile, and from 0.01 to 3.0 per cent by weight (based on the solution) of sulfuric acid.

2. A fiber spinning solution comprising a solvent for fiber-forming acrylonitrile polymers, polymer of monomeric substances of which from two to ten percent of the total monomer is a vinylpyridine and at least 80 percent is acrylonitrile, in polymeric form, and from 0.05 to 1.0 percent by weight (based on the solution) of sulfuric acid.

3. A fiber spinning solution comprising a solvent for fiber-forming acrylonitrile polymers, a copolymer of 90 to 98 percent acrylonitrile and from two to ten percent vinylpyridine, and from 0.01 to 3.0 percent by weight (based on the solution) of sulfuric acid.

4. A fiber spinning solution comprising a solvent for fiber-forming acrylonitrile polymers, a blend of a polymer of at least 90 percent acrylonitrile and a polymer of at least 30 percent of vinylpyridine, said polymers being so propora n on conm'ri in a N di ehvlaeta l l ion o po y er o .bsta" cesc hich fr m tw tot thet tali ionomer a. vinylpyridi and at least '80 percent is acrylonitrile in polye1jic Iprm. and from. 0.05 to, 1.0, percent by ed or'i'th "'luti' oiisulfuric acid.

a jlll dimethylac amide reo ter'ilpercent Orrin ume,,;ena from 0.05 to. 1.0

' solution) ofsulpertentgt wei ntrtased or j ill i to produce polymer having from two to ten percentof vinylpyridine in polymeric form, and from 0.01 to 3.0 percent by weight (based on the solution) of sulfuric acid.

10. A fiber spinning composition comprising a N,N-dimethy1acetamide solution of a blend of polymer of at least percent acrylonitrile and a polymer of at least 30 percent vinylpyridine, said polymers being blended in such proportions so as to produce polymer having from two to ten percent vinylpyridine in polymeric form, and from 0.05 to 1.0 percent by weight (based on the solution) of sulfuric acid.

11. A fiber spinning solution comprising a solvent for fiber-forming acrylonitrile polymers, a blend of a polymer of at least 90 percent acrylonitrile and up to ten percent of a monomer oi the group consisting of vinyl acetate and other, vinyl esters of carboxylic acids having up to four carbon atoms, vinylchloroacetate, methyl methacrylate, methyl acrylate, other alkyl acrylates and methacrylates wherein the alkyl radical has up to four carbon atoms, styrene, other vinyl substituted aromatc hydrocarbons, vinylidene chloride, diethyl fumarate, diethyl maleate, other alkyl fumarates and alkyl maleates wherein the alkyl radical has up to four carbon atoms and methacrylonitrile; and a polymer of at least 30 percent of vinylpyridine and up to 70 percent of acrylonitrile; and from 0.01 to 3.0 percent by weight (based on the solution) of sulfuric acid said blend of polymers being so proportioned so as to provide vinylpyridine to the extent of from two to ten percent of the total polymerized monomer.

12. A fiber spinning solution comprising a solvent for fiber-forming acrylonitrile polymers, a blend of a polymer of at least 90 percent acrylonitrile and up to ten percent of a monomer of the group consisting of vinyl acetate and other vinyl esters of carboxylic acids having up to four carbon atoms, vinylchloroacetate; methyl methacrylate; methyl acrylatefother alkyl acrylates and methacrylates wherein the alkyl radical has up to four carbon atoms, styrene,',other vinyl substituted aromatic hydrocarbons, vinylidene chloride, diethyl' fumarate, diethyl maleate, other alkyl fumarates and'alkylmaleates wherein the alkyl radical has up to four carbon atoms and methacrylonitrile; and a polymer of at least 30 percent of vinylpyridine and up to '70 percent of acrylonitrile; and from 0.05 to 1.0 percent by weight (based on the solution) of sulfuric acid said blend of polymers beingso proportioned so as to provide vinylpyridi'n'e to vthe extent'oi from two to ten percent of the totaljpohlmerized monomer. '1 i 13, A fiber spinning composition comprising a N,N-dimethylacetamide solution of a blender a polymer of at least 90 percent acrylonitrile and up to ten percent of a monomer of the group'consisting of vinyl acetate and other vinyl esters of carboxylic acids having'up to four carbon atoms, vinylchloroacetate, methyl methacrylate, methyl acrylate, other alkyl acrylates and methacrylates wherein thealkyl' radical has up to four carbon atoms, styrene, otheryinyl substituted aromatic hydrocarbons, vinylidene chloride, diethyl inmarate, diethyl maleate, other 'alkyl fumarates-and alkyl maleates wherein the alkyl radical has up to four carbon atoms and methacrylonitrilef and a polymer of at least 30per cent of vinylpyridine and up to 70 percent of acrylonitrile; andgfrom 0.01 to 3.0 percentby weight (based on the solution) of sulfuric acid saidblend of polymers being'so proportioned so as to provide vinylpyridine tothe extent of from two to ten percent of the total polymerized monomer.

14. 'A fiber spinningcomposition comprising a N,N-dimethylacetamide solution of a, blend of a polymer of at least 90 percent acrylonitrile and up" totenpercent of a monomer of the group consisting of vinyl acetate and other vinyl esters of carboxylic acids having up to four carbon atoms, vinylchloroacetate, methyl methacrylate, methyl acrylate, other alkyl acrylates and methacrylates wherein .the alkyl radical has up to four carbon atoms, styrene, other vinyl substituted aromatic hydrlocarbons, vinylidene chloride, diethyl', vfumarate, diethyl maleate, other alkyl fumarates and alkyl maleates wherein the alkyl radical has up to' four carbon atoms and methacrylonitrile; and a polymer of at least percent of vinylpyridine and up to percent of acrylonitrile; and from 0.05 to 1.0 percent by weightv (based on the solution) of sulfuric acid said blend of polymers being so proportion so as to pr ovide' vinylpyridine to the extent of from two toten per centof the total polymerized monomer.

ALFRED B. CRAIG.

" REFERENCES CITED UNITED STATES PATENTS Name Date Scheiderbauer Mar. 28, 1950 Number 

1. A FIBER SPINNING SOLUTION COMPRISING A SOLVENT FOR FIBER-FORMING ACRYLONITRILE POLYMERS, POLYMER OF MONOMERIC SUBSTANCES OF WHICH FROM TWO TO TEN PERCENT OF THE TOTAL MONOMER IS A VINYLPYRIDINE AND AT LEAST 80 PERCENT IS ACRYLONITRILE, AND FROM 0.01 TO 3.0 PER CENT BY WEIGHT (BASED ON THE SOLUTION) OF SULFURIC ACID. 